Cut out pieces from uncastrated boars may develop a bad smell, the so-called boar taint, when heated. In castrated boars, on the other hand, such obnoxious smells rarely appear. Male pigs are therefore usually castrated at a young age in order to prevent the meat therefrom from displaying the unpleasant boar taint when prepared later in the household. In other connections, the castration of male pigs has an unfavourable effect on the animals, as their utilization of the feeding stuff declines, their sickness rate increases and the meat percentage of the carcasses simultaneously falls.
The presence of certain indole compounds in the pork produces this very unpleasant boar taint when heated. Especially the compounds skatole and indole play a very important role. A good correlation has thus been found between the contents in the pork of skatole and indole, respectively, and the development of the boar taint. So far it has not been possible to determine these compounds specifically by a method which can be used in slaughter-houses in an economically acceptable manner.
WO 83/00928 (Slagteriernes Forskningsinstitut) discloses a method for the detection of boar taint by preparing an extract of a meat and/or fat sample, reacting said extract with a color reagent, for which the color intensity developed at certain wavelengths exhibit a statistical relationship with boar taint, determining the transmittance or absorbance of the reacted extract at one or more such wavelengths, and inserting the recorded values in the said statistical relationship.
DK patent No. 154,667 (Slagteriernes Forskningsinstitut) discloses a method for the determination of the degree of boar taint, whereby a sample of meat is extracted with a polar organic solvent, whereupon, optionally following a purification, the extract is analyzed by spectrophotometry or flourometry to determine one or more parameters which are statistically correlated with the development of boar taint. In one embodiment, (also disclosed in WO 83/00928) the degree of boar taint in pork is determined by homogenizing a weighed sample of lard and extracting said sample with tris-(hydroxymethyl)-amino-methane and acetone. A color reagent is added to the extract and the absorbance is measured spectrophotometricly in a wavelength range from 400 to 800 nm. The method is suitable for use in large slaughter-houses, where 1200-1400 samples are analyzed daily. In small slaughterhouses, where for instance less than about 500 samples are to be analyzed daily, the individual analysis will be too costly, as the analytical apparatus is expensive. By the method skatole and indole are not specifically determined, but rather the total contents of skatole equivalents of the sample.
The method disclosed in DK patent No. 154,667 is to a large extent used in Danish slaughterhouses and by means of a standardized spectrophotometric method a limit for the rejection of pigs has been set at the maximum amount of 0.25 ppm skatole equivalents.
The inventor of the present invention has carried out a regression analysis of the test results which are stated in DK patent No. 154,667 in Table I page 15 and Table II, page 17. The correlation factors thereby found are stated below.
When measuring meat extracts fluorometrically, a correlation factor to an organoleptic evaluation of the smell of 0.72 was obtained, while for lard extracts a correlation factor to an organoleptic evaluation of the smell of 0.24 was obtained. When comparing samples of lard analyzed by flourometry and by spectrophotometry, respectively, a correlation factor between the two analytical methods of 0.13 was obtained, and the correlation factor between the spectrophotometric measurement and the subjective estimate of the smell was 0.70. Calculations have been made on the basis of the results in Table II of the above DK patent of the fluorometric and spectrophotometric measurements both with and without the 8 young sows stated in page 17, lines 28-30 of the patent. Whether the calculations have been carried out with or without the 8 young sows, does, however, not change the importance of the results. A correlation factor of 1.00 corresponds to a correlation of 100%.
It may thus be concluded that the method disclosed in DK patent No. 154,667 is unsuitable for determining the degree of boar taint by spectrofluorometry on samples of lard.
It is thus the object of the present invention to provide a method for determining the degree of boar taint in pork whereby the compounds which, when heated, cause the unpleasant smell may be determined more specifically. It is thereby possible with greater certainty to point out those carcasses which, when prepared, will produce the boar taint which is unacceptable to the consumer, and thereby to prevent an unnecessary rejection of pork.
It is also the object of the present invention to provide a simple and relatively inexpensive method for the determination of the degree of boar taint, said method being especially suitable for use in small slaughterhouses which cannot bear the cost of investing in complicated and expensive analytical equipment.
Further, it is an object of the invention to provide a practical sample container for selecting a sample of fat where a prepared sample may be taken directly from the sample container, said sample being ready for injection into an analytical apparatus, for instance a HPLC apparatus.